The present invention relates to the decomposition of organic hydroperoxides to hydroxy-substituted organic compounds and carbonyl compounds in the presence of a particulate catalyst containing highly fluorinated polymer having sulfonic acid groups.
Commercial processes for the manufacture of hydroxy-substituted organic compounds, particularly aromatic compounds such as phenol and hydroquinone, often employ reaction routes that require the decomposition of organic hydroperoxides. For example, phenol is manufactured from cumene by converting it to the hydroperoxide followed by decomposition to phenol and acetone. The hydroperoxide decomposition reaction is an acid-catalyzed reaction and a concentrated sulfuric acid solution at temperatures in the range of 50-100xc2x0 C. is typically employed in commercial processes.
Though it provides effective catalysis, the use of sulfuric acid for the cumene hydroperoxide decomposition reaction has disadvantages. Since it is a homogenous catalyst, it is necessary to employ one or more process steps to separate it from the product mixture. The spent sulfuric acid must be neutralized and disposed of. Moreover, using sulfuric acid causes the product mixture to contain significant percentages of undesirable side products which reduce yields and require additional process steps for removal.
U.S. Pat. No. 4,322,560 discloses using a thin film of solid acid catalyst of perfluorocarbon polymer containing pendant sulfonic acid groups for the decomposition of organic hydroperoxides. However, the reaction rate is not sufficiently high at desirable process temperatures for the process to be particularly useful commercially. PCT Publication No. WO 96/19288, published Jun. 27, 1996, discloses catalysts which comprise porous microcomposites of perfluorinated ion exchange polymer and a metal oxide network. Numerous reactions are disclosed in this publication including the decomposition of organic hydroperoxides. While decomposition results using catalysts disclosed in this publication, the reaction rate again is not sufficiently high at desirable process temperatures to be particularly useful commercially.
The invention provides a process for the manufacture of a hydroxy-substituted organic compound comprising decomposing an organic hydroperoxide in the presence of a catalyst containing highly fluorinated polymer having sulfonic acid groups, the catalyst being in the form of particles of which at least about 20 weight % have a particle size less than about 300 xcexcm. In a preferred form of the invention, the catalyst is selected from the group consisting of (a) particles of highly fluorinated polymer having sulfonic acid groups and (b) particles of porous microcomposite of a metal oxide network and highly fluorinated polymer having sulfonic acid groups. Preferably, the process provides for the manufacture of a hydroxy-substituted aromatic compound comprising by the decomposition of a compound of the formula Arxe2x80x94C(CH3)2O2H, wherein Ar is a substituted or unsubstituted mononuclear or polynuclear aromatic group.
It has been discovered that a process employing catalyst particles having a particle size in accordance with the present invention increases the rate of the decomposition reaction and can provide higher reaction rates than in existing processes. In addition, hydroxy-substituted organic compounds are produced in high yield at moderate temperatures and in higher purity, i.e., with fewer undesirable side products than in existing commercial processes.
The invention also provides a process for the manufacture of 2,2-Bis(4-hydroxyphenyl)-propane (hereinafter referred to as Bisphenol A). The process includes:
(a) decomposing cumene hydroperoxide in the presence of a catalyst containing highly fluorinated polymer having sulfonic acid groups to form a decomposition product mixture containing phenol and acetone; and
(b) reacting the phenol and acetone of the decomposition product mixture in the presence of catalyst containing highly fluorinated polymer having sulfonic acid groups under conditions which promote the formation bisphenol A.
In a preferred embodiment of the process, at least a portion of the phenol and acetone of the decomposition product mixture is not separated from the catalyst prior to the reaction to form bisphenol A and the catalyst used for the decomposition is the same catalyst that is used for the reaction to bisphenol A.
The catalyst employed in accordance with the present invention contains highly fluorinated polymer having sulfonic acid groups. xe2x80x9cHighly fluorinatedxe2x80x9d means that at least 90% of the total number of univalent atoms in the polymer are fluorine atoms. Most preferably, the polymer is perfluorinated.
Preferably, the polymer of the catalyst comprises a polymer backbone with recurring side chains attached to the backbone, the side chains carrying the sulfonic acid groups. Possible polymers include homopolymers or copolymers of two or more monomers. Copolymers are typically formed from one monomer which is a nonfunctional monomer and which provides carbon atoms for the polymer backbone. A second monomer provides carbon atoms for the polymer backbone and also contributes the side chain carrying the sulfonic acid group or its precursor, e.g., a sulfonyl halide group such a sulfonyl fluoride (xe2x80x94SO2F), which can be subsequently hydrolyzed to a sulfonic acid functional group. For example, copolymers of a first fluorinated vinyl monomer together with a second fluorinated vinyl monomer having a sulfonyl fluoride group (xe2x80x94SO2F) can be used. Possible first monomers include tetrafluoroethylene (TFE), hexafluoropropylene, vinyl fluoride, vinylidine fluoride, trifluoroethylene, chlorotrifluoroethylene, perfluoro (alkyl vinyl ether), and mixtures thereof. Possible second monomers include a variety of fluorinated vinyl ethers with sulfonic acid functional groups or precursor groups which can provide the desired side chain in the polymer. Additional monomers can also be incorporated into these polymers if desired. TFE is a preferred monomer.
A class of preferred polymers for use in the present invention include a highly fluorinated, most preferably perfluorinated, carbon backbone and the side chain is represented by the formula xe2x80x94(Oxe2x80x94CF2CFRf)axe2x80x94Oxe2x80x94CF2CFRxe2x80x2fSO3H, wherein Rf and Rxe2x80x2f are independently selected from F, Cl or a perfluorinated alkyl group having 1 to 10 carbon atoms, and a=0, 1 or 2. The preferred polymers include, for example, polymers disclosed in U.S. Pat. No. 3,282,875 and in U.S. Pat. Nos. 4,358,545 and 4,940,525. One preferred polymer comprises a perfluorocarbon backbone and the side chain is represented by the formula xe2x80x94Oxe2x80x94CF2CF(CF3)xe2x80x94Oxe2x80x94CF2CF2SO3H. Polymers of this type are disclosed in U.S. Pat. No. 3,282,875 and can be made by copolymerization of tetrafluoroethylene (TFE) and the perfluorinated vinyl ether CF2xe2x95x90CFxe2x80x94Oxe2x80x94CF2CF(CF3)xe2x80x94Oxe2x80x94CF2CF2SO2F, perfluoro(3,6-dioxa-4-methyl-7-octenesulfonyl fluoride) (PDMOF), followed by hydrolysis of the sulfonyl halide groups to sulfonate groups, and acid exchange to convert the sulfonate groups to the proton form. One preferred polymer of the type disclosed in U.S. Pat. Nos. 4,358,545 and 4,940,525 has the side chain xe2x80x94Oxe2x80x94CF2CF2SO3H. This polymer can be made by copolymerization of tetrafluoroethylene (TFE) and the perfluorinated vinyl ether CF2xe2x95x90CFxe2x80x94Oxe2x80x94CF2CF2SO2F, perfluoro(3-oxa-4-pentenesulfonyl fluoride) (POPF), followed by hydrolysis and acid exchange.
In this application, xe2x80x9cion exchange ratioxe2x80x9d or xe2x80x9cIXRxe2x80x9d is defined as the number of carbon atoms in the polymer backbone in relation to the cation exchange groups. A wide range of IXR values for the polymer are possible. Typically, however, the IXR range used for the catalyst is usually about 7 to about 33. For perfluorinated polymers of the type described above, the cation exchange capacity of a polymer is often expressed in terms of equivalent weight (EW). For the purposes of this application, equivalent weight (EW) is defined to be the weight of the polymer in acid form required to neutralize one equivalent of NaOH. In the case of a sulfonic acid polymer in which the polymer comprises a perfluorocarbon backbone and the side chain is xe2x80x94CF2xe2x80x94CF(CF3)xe2x80x94Oxe2x80x94CF2xe2x80x94CF2xe2x80x94SO3H, the equivalent weight range which corresponds to an IXR of about 7 to about 33 is about 700 EW to about 2000 EW. IXR for this polymer can be related to equivalent weight using the following formula: 50 IXR+344=EW. While generally the same IXR range is used for sulfonic acid polymers disclosed in U.S. Pat. Nos. 4,358,545 and 4,940,525, the equivalent weight is somewhat lower because of the lower molecular weight of the monomer unit containing the sulfonic acid group. For the IXR range of about 7 to about 33, the corresponding equivalent weight range is about 500 EW to about 1800 EW. IXR for this polymer can be related to equivalent weight using the following formula: 50 IXR+178=EW.
IXR is used in this application to describe either hydrolyzed polymer which contains functional groups or unhydrolyzed polymer which contains precursor groups which will subsequently be converted to the functional groups during the manufacture of the catalyst.
The highly fluorinated polymer having sulfonic acid groups used in the process of the invention preferably has ion exchange ratio of about 8 to about 23, more preferably about 9 to about 14 and most preferably about 10 to about 13.
Other ion exchange groups such as carboxylic acid groups may be present in the highly fluorinated polymer provided that a sufficient quantity of sulfonic acid groups are present in the polymer for the catalyst to provide a suitably high reaction rate for a commercial process. In addition, the polymer may be partially cation-exchanged with some of the sulfonic acid groups present in cation-exchanged form, i.e., sodium, potassium, etc., provided that a sufficient quantity of sulfonic acid groups are retained. Preferably, the polymer contains only sulfonic acid groups and is at least about 80% acid exchanged, more preferably, at least about 90% acid exchanged, still more preferably at least about 98% acid exchanged, and most preferably substantially completely acid exchanged.
It has been discovered that use of catalyst particles in a specified size range, disclosed below, increases the rate of the decomposition reaction dramatically. Particle size is the number average particle size, and is measured by optical and electron microscopy. The particles of catalyst used in a process in accordance with the invention can have any of a variety of shapes and may be highly irregular. When particles have an aspect ratio, particle size refers to the longest dimension of the particles. By having an aspect ratio is meant that the particles are not round or spherical.
In the process according to the invention, the catalyst may contain some larger catalyst particles provided that a sufficient quantity particles of the specified size are present to achieve the desired result. However, larger particles will reduce the effectiveness of the catalyst per unit of weight and it is preferred that substantial quantities of larger particles to be excluded. Therefore, at least about 20 weight % of the catalyst, preferably at least about 30 weight % of the catalyst, more preferably at least about 40 weight % of the catalyst, still more preferably at least about 65 weight % of the catalyst, still more preferably at least about 80 weight %, still more preferably at least about 90 weight %, and most preferably substantially all of the catalyst has a particle size less than about 300 xcexcm. It is further preferable for the above-stated weight percentages of the catalyst to have a particle size less than about 100 xcexcm. The minimum particle size for the catalyst is preferably greater than about 0.02 xcexcm, more preferably greater than about 0.05 xcexcm, most preferably greater than about 0.1 xcexcm.
Preferably, the particles are in a size range which enables them to be separated from the product mechanically using techniques typically used for heterogeneous catalysts in liquid systems. If desired, a fixed bed of the catalyst can be used.
For the practice of the present invention, it is preferred that the catalyst be in the form of particles of the polymer itself, i.e., highly fluorinated polymer having sulfonic acid groups, or in the form of particles of porous microcomposite of a metal oxide network and highly fluorinated polymer having sulfonic acid groups. Porous microcomposites which are useful in the practice of the invention are described in PCT Publication No. WO 96/19288, published Jun. 27, 1996. The porous microcomposites disclosed comprise a perfluorinated ion-exchange polymer entrapped within and highly dispersed throughout a network of metal oxide. The weight percentage of perfluorinated ion-exchange polymer in the microcomposite is from about 0.1 to 90 percent, preferably from about 5 to about 80 percent, and most preferably about 5 to about 25 percent. The size of the pores in the microcomposite is about 0.5 nm to about 75 nm and, optionally, further comprises pores having a size in the range of about 75 nm to about 1000 nm.
The microcomposites described in PCT Publication No. WO 96/19288 exist as particulate solids which are porous and glass-like in nature and are structurally hard, similar to dried silica gels. The porous nature of the microcomposites is evident from their high surface areas.
xe2x80x9cMetal oxidexe2x80x9d signifies metallic or semimetallic oxide compounds, including, for example, alumina, silica, titania, germania, zirconia, alumino-silicates, zirconyl-silicates, chromic oxides, germanium oxides, copper oxides, molybdenum oxides, tantalum oxides, zinc oxides, yttrium oxides, vanadium oxides, and iron oxides. Preferably, the network of metal oxide of the microcomposite is selected from the group consisting of: silica, alumina, titania, germania, zirconia, alumino-silicate, zirconyl-silicate, chromic oxide and iron oxide. Silica is the most preferred metal oxide.
A process for manufacture of the microcomposites is disclosed in PCT Publication No. WO 96/19288 and employs a metal oxide precursor which is employed in a sol-gel process to produce a metal oxide in the microcomposite. This process is useful in the manufacture catalysts for the practice of the present invention provided that the size of the composite particles is reduced as described hereinafter.
Catalyst particles of a size suitable for the present invention may be formed by mechanically grinding (a) highly fluorinated polymer having sulfonic acid groups or (b) porous microcomposites of metal oxide and highly fluorinated polymer having sulfonic acid groups. For grinding the polymer itself, particle size in the desired range can be suitably accomplished by cryogrinding. Size reduction of the porous microcomposites can be suitably accomplished by grinding at room temperature. The resulting particles can be sieved or otherwise treated if necessary to separate particles that are less than about 300 xcexcm, and preferably less than about 100 xcexcm, for use in the process of the invention.
Alternatively, suitable catalyst can be produced by spray drying a liquid, preferably aqueous, dispersion of highly fluorinated polymer having sulfonic acid groups and/or such a dispersion also containing metal oxide precursor. Spray drying using a commercial spray drier such as that produced by Niro, of Columbia, Md., can produce particles typically in the range of about 0.5 xcexcm to about 50 xcexcm.
The process in accordance with the invention produces hydroxy-substituted organic compounds by decomposing organic hydroperoxide. The process is especially useful in the manufacture of a hydroxy-substituted aromatic compound comprising decomposing a compound of the formula Arxe2x80x94C(CH3)2O2H, wherein Ar is a substituted or unsubstituted mononuclear or polynuclear aromatic group. Two preferred reactions are (1) the decomposition of cumene hydroperoxide and (2) the decomposition of diisopropylbenzene dihydroperoxide. 
The process is preferably carried out in organic solvents such as acetone, dichlorobenzene, benzene, or chloroform. In the preferred forms of the invention, the decomposition of cumene hydroperoxide and the decomposition of diisopropylbenzene dihydroperoxide in which acetone is a reaction product, a preferred organic solvent is acetone.
Preferably, the temperature of the reaction is about xe2x88x9215xc2x0 C. to about 150xc2x0 C., and most preferably about 20xc2x0 C. to about 100xc2x0 C. If the chosen reaction temperature is above the boiling point of the solvent at atmospheric pressure, the reaction can be carried out in a pressure vessel.
The highly fluorinated polymer having sulfonic acid catalyst of small particle size described herein before or of larger particle size, is also useful for the manufacture of 2,2-Bis(4-hydroxyphenyl)-propane (Bisphenol A). In this reaction, cumene hydroperoxide is decomposed in the presence of catalyst containing highly fluorinated polymer containing sulfonic acid groups to form a decomposition product mixture containing phenol and acetone. The phenol and acetone from the decomposition product mixture is reacted in the presence of the fluoropolymer sulfonic acid catalyst under conditions which form bisphenol A. Preferably, at least a portion of the phenol and acetone of the decomposition product mixture is not separated from the catalyst prior to the reaction to form bisphenol A and the catalyst used for the decomposition is the same catalyst that is used for the reaction to bisphenol A. The reaction to make bisphenol A proceeds at reasonable rates at the same temperatures as the hydroperoxide decomposition. Preferably, the mole ratio of phenol relative to acetone is increased prior to reaction to form bisphenol A, and such increase is preferably achieved by removing some acetone from the decomposition product mixture. The catalyst present during the decomposition of cumene hydroperoxide and in the phenol/acetone reaction is preferably in the form of particles wherein at least about 20 weight % of the catalyst, more preferably at least about 30 weight % of the catalyst, still more preferably at least about 40 weight % of the catalyst, still more preferably at least about 65 weight % of the catalyst, still more preferably at least about 80 weight %, still more preferably at least about 90 weight %, and most preferably substantially all of the catalyst has a particle size less than about 300 xcexcm. It is further preferable for the above-stated weight percentages of the catalyst to have a particle size less than about 100 xcexcm. The minimum particle size for the catalyst is preferably greater than about 0.02 xcexcm, more preferably greater than about 0.05 xcexcm, most preferably greater than about 0.1 xcexcm.